Re: help: pandas and 2d table

Tim Williams <tjandacw@gmail.com> wrote or quoted:

e.where.html#pandas.DataFrame.where>

  Threw together a quick thing with "where", see how it looks.

import pandas as pd

# Warning! Will overwrite the file 'file_20240412201813_tmp_DML.csv'!
with open( 'file_20240412201813_tmp_DML.csv', 'w' )as out:
    print( '''obj,foo1,foo2,foo3,foo4,foo5,foo6
foo1,aa,ab,zz,ad,ae,af
foo2,ba,bb,bc,bd,zz,bf
foo3,ca,zz,cc,cd,ce,zz
foo4,da,db,dc,dd,de,df
foo5,ea,eb,ec,zz,ee,ef
foo6,fa,fb,fc,fd,fe,ff''', file=out )

# Note the "index_col=0" below, which is important here!
df = pd.read_csv( 'file_20240412201813_tmp_DML.csv', index_col=0 )

df = df.where( df == 'zz' ).stack().reset_index()
result ={ 'zz': list( zip( df.iloc[ :, 0 ], df.iloc[ :, 1 ]))}

print( result )

  Prints here:

{'zz': [('foo1', 'foo3'), ('foo2', 'foo5'), ('foo3', 'foo2'), ('foo3', 'foo6'), ('foo5', 'foo4')]}

  .